A mysterious hypnotist reverts his beautiful assistant back into the form of a prehistoric sea monster that she was in a past life.

Chester Morrisas Dr. Carlo Lombardi
Marla Englishas Andrea Talbott / Elizabeth Wetherby
Tom Conwayas Timothy Chappel
Cathy Downsas Dorothy Chappel
Lance Fulleras Dr. Ted Erickson
Ron Randellas Police Lt. Ed James
Frieda Inescortas Mrs. Chappel
Frank Jenksas Plainclothes Sgt. with Lt James
El Brendelas Olaf, the butler
Paul Dubovas Johnny, the barker